Sheath for a test tube



FIG. 1 is a side view of a sheath for a test tube showing my new design, the design with the sheath being rotationally symmetric;

FIG. 2 is a bottom view of the design;

FIG. 3 is a top view of the design;

FIG. 4 is a top perspective view of the design; and,

FIG. 5 is a bottom perspective view of the design. 

CLAIM The ornamental design for a sheath for a test tube, as shown and described. 